Genetic drift in small, divided populations will tend to?

Question

a. increase genetic variability both within and between populations
b. decrease genetic variability both within and between populations
c. increase genetic variability within a population but decrease genetic variability between populations
d. decrease genetic variability within a population but increase genetic variability between populations

Answer 1

D

Genetic drift causes genes to become either more or less common by random chance in a single small population. Therefore, within the populations considered separately, they are becoming less variable.

When comparing two isolated populations, genetic drift will tend to make those populations more different from one another (increase genetic variability) because chances are that genetic drift will occur in different 'directions' between the two populations.

Imagine you and a friend each roll a die 10 times (there are 10 members in each of your populations). By random chance, you may get four 5's, but your friend may get three 8's. Variability within the populations is low, but variability between your two populations is high (you are mostly 5's and your friend is mostly 8's).

Answer 2

d is the right answer. The separated populations with drift apart genetically. But, within each population individuals will stay closer to the same as every other individual.